Variable inlet guide vanes for gas turbine engine compressors may be actuated using a spur ring gear meshed with spur pinions. Such arrangements typically require the vanes to be pivotable about an axis parallel to the rotational axis of the ring gear. Other arrangements are known for vanes pivotable about a radial axis. In existing gear actuating systems, backlash and angle accuracy is typically solely determined by the manufacturing tolerances of the system's components, and accordingly the backlash may be relatively high and/or possible adjustment of the backlash may be limited.